Gas generator

Abstract

A gas generator including a plug (24) having a header part (45) and two or more electrode pins (22, 23), a thin-film bridge (25) having electrode pads (41, 42), and a squib (10) in which upon supply of electric current to the thin-film bridge (25) via the electrode pins (22, 23), the thin-film bridge (25) is activated to ignite ignition materials (26, 27), wherein the thin-film bridge (25) is arranged into a hollow (32) prepared at the plug (24) in such a manner that the thin-film bridge (25) is kept approximately on a level with the head (35) of the electrode pins (22, 23) and the header part (45) of the plug (24), the thin-film bridge (25) is connected by wire bonding to the electrode pins (22, 23) at the electrode pad parts (41, 42), and at least either of the electrode pad (41) or (42) of the thin-film bridge (25) is connected by the wire bonding to a metal part of the header part (45) of the plug (24).

Description

TECHNICAL FIELD[0001]The present invention relates to a gas generator suitable for inflating an airbag for side impact, a curtain airbag and the like.BACKGROUND ART[0002]An airbag is known as a safety system for protecting a passenger from an impact resulting from a collision of an automobile. The airbag is activated by a large quantity of a high-temperature and high-pressure gas generated by a gas generator. Conventionally, gas is generated by gas generators according to two roughly-categorized methods. One is a pyro inflator method in which all gases are generated by burning solid gas generants (for example, refer to Patent Document 1). The other is a hybrid inflator method in which a gas cylinder containing a high pressure gas and a small quantity of explosive compositions for supplying heat to a high pressure gas in the gas cylinder are used to discharge a large quantity of a high pressure gas (for example, refer to Patent Document 4).[0003]Where gas generant compositions includ...

AI Technical Summary

Benefits of technology

The present invention relates to a gas generator suitable for inflating airbags in automobiles. The technical problem addressed by the invention is to improve the ignition and burning performance of gas generators used in airbags by using high-temperature and high-pressure gas generants that are low in ignitability and slow in burning velocity, without adding excessive weight or complexity to the gas generator. The invention also addresses the issue of delayed ignition in the gas generator caused by low-reactive materials and the need for a high-pressure gas inside the gas cylinder to reliably seal it.

Problems solved by technology

Where gas generant compositions include low reactive materials such as guanidine derivatives and ammonium nitrate as its compositions, there poses a problem that the gas generants are low in ignitability, in addition to a slow burning velocity.

Therefore, only a slight delay in activation of the gas generator will give such a serious impact that the airbag cannot exhibit a sufficient performance.

Gas generants, which are low in ignitability, will take a longer time to ignite on a squib inside the gas generator, resulting in a delayed ignition of the gas generator.

However, the thus increased quantity of the propellant will lead to an increase in total calorific value of the gas generator itself, which consequently increases the weight of a filter member for cooling the gas and makes the gas generator larger in size.

Under these circumstances, conventional gas generators have not been made smaller in size or lighter in weight.

However, this gas generator needs a process for notching the outer peripheral end surface of the partition member to provide the seal member such as the O-ring, thereby increasing a cost of manufacturing the gas generator, which poses a problem.

However, since the gas generator must keep a high pressure gas in a gas cylinder, the high pressure gas may escape from the gas cylinder in the course of as long as 15-year life period as a gas generator, thereby resulting in a failure of providing a sufficient effect, where sealing is insufficient.

This structure is able to rupture the rupture diaphragm without fail but requires a hollow piston or the like, thereby making the gas generator structurally complicated, which also poses a problem.

However, an increased quantity of the propellant requires a chamber for accommodating the propellant, thereby making it difficult to miniaturize the gas generator.

Further, in this instance, it is difficult to rupture the rupture disk simultaneously with ignition of the squib.

This generator is unable to sufficiently heat the gas from the gas cylinder, which poses another problem.

However, where the squib is connected with an electric-conductive epoxy resin and used in a gas generator for an automobile, it is exposed to a high-temperature environment on blazingly hot days in summer, which may result in a change in resistance value of the electric-conductive epoxy resin.

Further, the resistance value is easily affected by the surface condition of an electrode even at an initial stage of assembly, resulting in a great variance in initial resistance value, which poses a problem.

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